Galena Group | |
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Stratigraphic range: Darriwilian-Sandbian | |
Unidentified Trochonema from the Galena Group | |
Type | Group |
Sub-units | Decorah Shale, Dunleith Formation, Wise Lake Formation, Dubuque Formation |
Underlies | Maquoketa Group |
Overlies | Platteville Limestone |
Location | |
Country | United States |
Extent | Minnesota, Wisconsin and Illinois |
Paleozoic Stratigraphy of the Upper Midwest, USA |
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Dates approximate |
Maquoketa Group (446–440 Ma) |
Galena Group (454–446 Ma) |
|
Platteville Limestone (455–454 Ma) |
Glenwood Shale (~455 Ma) |
St. Peter Sandstone (~459–~455 Ma) |
Knox Unconformity (~470-~459 Ma) |
Knox Supergroup (~497-~470 Ma) |
The Galena Group or Galena Limestone refers to a sedimentary sequence of Ordovician limestone that was deposited atop the Decorah Shale. It is part of the Ordovician stratigraphy of the Upper Midwestern United States. It was deposited in a calm marine environment, and is fossiliferous.
References
- Raatz, William; Ludvigson, Greg (1996). "Depositional environments and sequence stratigraphy of Upper Ordovician epicontinental deep water deposits, eastern Iowa and southern Minnesota". Special Paper of the Geological Society of America. 306 – via ResearchGate.
- Mossler, J. and Benson, S., 1995, 1999, 2006, Fossil Collecting in the Twin Cities Area. Minnesota at a Glance: Minnesota Geological Survey: University of Minnesota.
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